A colorimetric probe for detection of Cu2+ by the naked eye and application in test paper.

A novel colorimetric probe RP1 was synthesized using rhodamine derivatives and heterocyclic compounds for the purpose of detecting Cu2+ . RP1 showed good selectivity, high sensitivity and affinity toward Cu2+ over other competing ions in CH3 OH-H2 O (1/1, v/v) solution. Absorbance intensity showed a good linear fit between probe R1 and Cu2+ over the concentration range 1-8 µM and the association constant was also calculated to be 1.145 × 105 M-1 . The sensing mechanism was deduced using Job's plot, Fourier transform infrared spectroscopy, and density functional theory studies. In addition, the colorimetric experiment indicated that probe RP1 could be made into test paper to detect Cu2+ with a colour change from colourless to pink.

A Highly Selective "Turn-on" Fluorescent Probe for Detection of Fe3+ in Cells.

A new "turn-on" fluorescent probe Py based on rhodamine and piperonaldehyde was designed and synthesized for detecting Fe3+ in cells. The free probe Py was non-fluorescent. While only upon addition of Fe3+, the significant increase of the fluorescence and color were observed which could be visible directly by "naked-eye". The probe Py shows high selectivity and sensitivity for Fe3+ over other common metal ions in EtOH-H2O (3/2, v/v) mixed solution. The association constant and the detection limit were calculated to be 4.81 × 104 M-1 and 1.18 × 10-8 mol/L respectively. The introduction of piperonaldehyde unit could increase probe rigidity which could enhance its optical properties. Meanwhile, the binding mode between Py and Fe3+ was found to be a 1:1 complex formation. The density functional theory (DFT) calculations were performed which would further confirm the recognition mechanism between probe Py and Fe3+. In addition, the probe has been proved to be reversible for detecting Fe3+. Moreover, the probe Py was used to detect Fe3+ in cells successfully.

Development of a Fluorescein-Based Probe with an "Off-On" Mechanism for Selective Detection of Copper (II) Ions and Its Application in Imaging of Living Cells.

Copper is a common metallic element that plays an extremely essential role in the physiological activities of living organisms. The slightest change in copper levels in the human body can trigger various diseases. Therefore, it is important to accurately and efficiently monitor copper ion levels in the human body. Recent studies have shown that fluorescent probes have obvious advantages in bioimaging and Cu2+ detection. Therefore, a novel Cu2+ probe (N2) was designed and synthesized from fluorescein, hydrazine hydrate and 5-p-nitrophenylfurfural that is sensitive to and can detect Cu2+ within 100 s. The response mechanism of the N2 probe to Cu2+ was studied by several methods such as Job's plots and MS analysis, which showed that the Cu2+ and the N2 probe were coordinated in a complexation ratio of 1:1. In addition, compared with other cations investigated in this study, the N2 probe showed excellent selectivity and sensitivity to Cu2+, exhibiting distinct fluorescence absorption at 525 nm. Furthermore, in the equivalent range of 0.1-1.5, there is a good linear relationship between Cu2+ concentration and fluorescence intensity, and the detection limit is 0.10 µM. It is worth mentioning that the reversible reaction between the N2 probe and Cu2+, as well as the good biocompatibility shown by the probe in bioimaging, make it a promising candidate for Cu2+ biosensor applications.

Novel rhodamine Schiff base type naked-eye fluorescent probe for sensing Fe3+ and the application in cell.

Three rhodamine schiff-base type fluorescent sensors R1-R3 for detecting iron ion (Fe3+), 2-furanacrolein rhodamine hydrazone (R1), furfural rhodamine hydrazone (R2) and 2-furanacrolein rhodamine ethylenediamine (R3) have been synthesized by using rhodamine B derivatives and furan derivatives as staring materials. And their recognition abilities for Fe3+ were studied by fluorescence spectroscopy. The result showed that R1 is a best selective probe for Fe3+ over other metal ions in EtOH/H2O (1:1, v/v) due to having 2-furanacrolein for unique space coordination structural. The recognition of Fe3+ and mechanism of the sensor were characterized and determined by fluorescence spectra and Fukui function. And the fluorescence intensity of the probe R1 for Fe3+ was proportional to its concentration with the linear correlation coefficient of 0.9965 and the binding constant of 7.66×104M-1. And the cell imaging experiment indicated a successful application of the probe R1 for Fe3+ in living cell.

Using molecular recognition of beta-cyclodextrin to determine molecular weights of low-molecular-weight explosives by MALDI-TOF mass spectrometry.

This study presents a novel method for determining the molecular weights of low molecular weight (MW) energetic compounds through their complexes of beta-cyclodextrin (beta-CD) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) in a mass range of 500 to 1700 Da, avoiding matrix interference. The MWs of one composite explosive composed of 2,6-DNT, TNT, and RDX, one propellant with unknown components, and 14 single-compound explosives (RDX, HMX, 3,4-DNT, 2,6-DNT, 2,5-DNT, 2,4,6-TNT, TNAZ, DNI, BTTN, NG, TO, NTO, NP, and 662) were measured. The molecular recognition and inclusion behavior of beta-CD to energetic materials (EMs) were investigated. The results show that (1) the established method is sensitive, simple, accurate, and suitable for determining the MWs of low-MW single-compound explosives and energetic components in composite explosives and propellants; and (2) beta-CD has good inclusion and modular recognition abilities to the above EMs.